


The Best Things Are Left Unsaid

by LunaWinchester4255



Category: Supernatural
Genre: Accidental Knotting, Alpha Castiel (Supernatural), Alpha Castiel/Omega Dean Winchester, Alpha/Beta/Omega Dynamics, Alpha/Omega, Beta Bobby Singer, Beta Ellen, Bottom Dean, Dean in Heat, First Kiss, First Time, M/M, Mating, Mating Bond, Mating Cycles/In Heat, Nesting, Nesting Dean, Omega Dean, Pregnancy, Rutting, Top Castiel, Unplanned Pregnancy
Language: English
Status: Completed
Published: 2017-02-27
Updated: 2017-02-27
Packaged: 2018-09-26 06:51:04
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 3,503
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9872336
Author URL: https://archiveofourown.org/users/LunaWinchester4255/pseuds/LunaWinchester4255
Summary: Castiel is Dean's tutor and they slowly fall in love, even though it's not said. Once Dean goes in heat, Cas pounces and Dean ends up pregnant. What happens when neither of them can pick up the phone?





	

**Author's Note:**

  * For [NavajoLovesDestiel](https://archiveofourown.org/users/NavajoLovesDestiel/gifts).



> This is my first ABO fic. Please be gentle.

When Dean started failing, he knew he was doomed. Not because he had to have a tutor, and not because the tutor was only four years older than him,  but because of who it was.

 

Castiel Novak. Adorable brown-haired, blue-eyed Alpha. He was built well, and Dean found his lips absolutely irresistible. Dean was head over heels in infatuation with the nerdy man, but that was only part of it. 

 

At first, Dean thought that his obsession with Castiel was purely a crush. He was a teenager, well… not anymore. He had just turned 18, so he couldn't justify his feelings for an older man as a kiddy crush. He was becoming a grown man and he enjoyed spending time with Castiel. 

 

When he first met Castiel, most of the things he thought of were purely sexual, and all he wanted was Castiel’s knot inside him. Whenever they were alone he wanted to beg the Alpha to bend him over or just crawl on top of him and fuck him.  But eventually those thoughts subsided (except when he found himself late at night with Castiel’s scent etched into his brain, his hands all over his lower region) and other things began to come to mind. 

 

Some time ago Castiel took Dean out for ice cream and pie as a reward for getting a B+ on a test, and that’s all Dean could think about, and he wanted to do more domestically romantic things with Cas. He wanted hugs from him and gentle kisses. But also a lot more.

 

Dean hoped that eventually he could tell Castiel about his feelings, but it seemed inappropriate since Cas showed no signs of feeling the same. The last thing Dean wanted to do was embarrass himself. Things would be incredibly awkward if Dean admitted to Castiel how badly he wanted his knot inside of him and then Cas rejected him. He could never look Cas in the face after that. 

 

Dean had just began Spring Break, and he decided to stay home since all his friends were heading out of town. 

Jess, Anna, and Gabe had headed to the lake and Dean knew he'd be presenting soon and there was a high chance he'd go into heat and the last thing he wanted was to be around drunk Alphas. 

\--

 

Dean flipped through the channels on the TV, sighing in boredom. 

Suddenly there was a knock on the door, the sudden sound caused Dean to jump. He stood up off of the couch and walked to the door and opened it and smiled at the sight of the blue-eyed male. “Hi, Cas. What's up?”

 

“Hello, Dean. I just wanted to stop by and ask...something.”

 

Dean tilted his head in confusion, seeing Cas was a bit indecisive about making the decision to pose the question. “Well?” Dean whispered.

 

“Would you like to go out to lunch with me? I know both of our spring breaks start tomorrow and I thought it'd be nice to hang out.”

 

“Like a date?” he gaped a little, butterflies suddenly rumbling the insides of Dean's stomach. 

 

Cas nodded hesitantly. “Will you go out on a date with me?”

 

“Yes! I-I mean yeah.. um come inside let me just let Aunt Ellen know...and I'll change out of my pjs…” he scratched behind his head and shut the door behind Castiel and walked to his aunt's room, knocking before opening the door.

 

“Aunt Ellen?” Dean poked his head in the room and Ellen was reading a book. 

 

“What is it hun?” she looked up, her full attention to the boy. 

 

“Um, I got asked out on a date...and I said yes. I was just letting you know since Bobby doesn't want me working…” he looked at his feet, not sure what she'd say.

 

“I understand, you don't want to be cooped up. But you're not going out in your pajamas.”

 

“I know. I'm going to change now...my date’s waiting.”

 

Ellen raised a brow. “Castiel?”

 

“Castiel.” he confirmed before walking out. 

\--

 

After changing and taking a deep breath, Dean rinsed his face off with cold water. His nerves were shot with excitement. What if he got to kiss Castiel? What if they held hands? He felt giddy, but tried to remain calm so Cas wasn't scared off by his enthusiasm. He exhaled and exited the bathroom, smiling softly at Castiel.

 

“Ready to go?” Cas held out his hand, inviting the Omega to beckon closer. 

 

Dean took his hand, their fingers lacing together before he stepped closer, nodding. He knew there was no way that he'd be able to contain his glee. He felt so out of character feeling like this around Castiel.

\--

First, Castiel took Dean to an old 50s-esque eatery, named Jaybird’s Diner in downtown Lawrence. 

 

“I've only been here once, with Gabriel and my mom when I was younger,” Cas hummed as the two were sat down in a booth.

 

“I think I remember being here with Bobby and Ellen and Sammy.”

 

Cas smiled and took Dean's hand on the table. “I'm glad you agreed to go out with me Dean. Thank you for giving me a chance.”

 

“Thank you for getting me out of the house... and of course.” 

“Speaking of which, I haven't seen you with your uncle in the garage. Did you get sick?”

 

Dean shook his head. “No, it's kind of a long story... Bobby wants me to be safe at home when I present--which could be any time now--so I've been in the house for a little while just to be safe.”

 

“You're an Omega?” 

 

Dean nodded. “I thought you knew that…” he could tell that Cas’ expression had changed greatly and he felt like that information disgusted him. “I-I'm sorry.” he began to pull his hand away but Cas tightened his grip reassuringly. 

 

“No need to be sorry. I didn't know that, I think it's cute.” he smiled softly.

 

“So, what's it like being an alpha?” Dean asked.

 

“It's overrated.” 

 

The waitress came over and took their orders, Dean getting a bacon cheeseburger and Cas got a regular hamburger.  

They chatted for awhile and laughed, having a good time altogether. Dean couldn't remember the last time he had that much fun. 

\--

Cas held Dean's hands outside of the front door, rubbing the backs of his hands and smiling.

 

“I had a lot of fun with you Dean…I'm glad we got to spend time together today.”

 

Dean smiled back at him and nodded. “Thank you for taking me out… will you be back around?”

 

“Of course. But I'm going out of town for a week to visit Michael and his soon-to-be wife, I can't reject social gatherings. I'll call you when I can though.”

 

Cas leaned in a bit, Dean's cheeks turning bright red.

 

He stepped closer, their lips pressing together and his hands slipping around Castiel’s neck. 

 

“Mm..” Dean practically melted into the kiss.

 

“What are you boys doing?” 

 

Dean jumped back, searching for the source of the voice.

His eyes landed on Bobby, Ellen next to him. 

 

Ellen hit him on the head with a newspaper. “Dammit, Bobby leave him alone. He's happy with Cas and they'd make a cute couple.” 

 

Cas kissed Dean's forehead and looked at him. “I'll see you around, Dean. Stay safe.”

\--

 

A week had passed, no word from Castiel. No call, no text. 

 

Dean was beginning to think that Castiel had lost interest, but he couldn't stop thinking about their kiss.

 

Did Castiel want more from Dean…? Did he want to be his alpha?

 

He shook his head and stared at the ceiling, knowing he'd have to wait until next Sunday before seeing Castiel again because that's when they had their study session.

 

He decided to swallow his pride and texted Cas, not wanting to seem desperate. 

 

_ Dean 6:45 pm _

 

  * __Hey,  how was the rehearsal dinner?__



 

 

_ Cas 6:49 pm _

 

  * __Uneventful. I'm sorry I haven't been able to reach you, the stress of family members has been getting to me.__



 

 

_ Dean 6:51 pm _

 

  * __Don’t sweat it, I understand. Will I see you next Sunday?__



 

 

_ Cas 6:52 pm _

 

  * __Of course. The layover is almost done. I'll be back in Kansas soon.__



 

 

_ Dean 6:59 pm _

 

  * __That's good to hear. Also, I had lots of fun last week. Thank you again.__



 

 

_ Cas 7:01 pm _

 

  * __It was my pleasure. I'll have to bring you up to Vermont, it's beautiful here. Maybe during the summer.__



 

 

_ Dean 7:03 pm _

 

  * __I'd like that. I have to go eat dinner now, I'll talk to you soon. Have a good night, be safe.__



 

 

_ Cas 7:05 pm _

 

  * __You too. I'll see you soon.__



 

 

The week went by incredibly slow, no text from Cas. No call, no nothing. Dean was on edge and began to crave the older man. Not sexually, per se, but he just wanted to be in Castiel’s arms and he definitely wanted to kiss him again.

 

On Monday, Dean studied for an upcoming test. He tried to keep Cas out of his mind. 

 

On Tuesday, he watched movies and browsed the internet. Ellen was talking about Cas to Bobby, and of course Dean heard. It seemed that Bobby had warmed up to Cas. Bobby wanted Dean to be happy, and that's all that mattered. 

 

Then Wednesday came around and the week seemed to be never-ending. 

 

Thursday rolled around and Dean found himself searching up restaurants in Vermont. Where would Cas take him? Would it be a date or would he want to go as friends?

 

Friday was uneventful. 

 

Saturday he spent napping. He felt a little under the weather and he didn't know why. Soon his clothes felt itchy and hot. They clung to his skin as if it wasn't 75 degrees in his room and throughout the house. 

 

On Sunday he was in shorts rather than jeans and a tank top. 

 

He heard a knock on the door and rushed over from the table (where his school work was) and opened the door.

 

“Hello, Dean.”

 

“Hey…” he looked at the man, his stomach twisting with nervousness and he looked down. It's been over two weeks and they only texted  once the entire time. Had he lost interest?

 

“Are you alright, Dean?” he reached for his hand but Dean pulled away before he could. “Dean, what's wrong?”

 

“If you didn't want to see me you should've said something. You didn't have to ignore me.”

 

“Ignore you?  Bobby said you were grounded so I shouldn't have texted. I didn't even think you had your phone, that's why I was so surprised last Sunday when you did.”

 

“You could have texted me to let you know that you were safe…”

 

“I'm sorry, Dean. You're right.”

 

Dean's hardened gaze softened and he reached for Castiel’s hand. “I can't be mad at you…n-ngh!” 

 

Dean's eyes shut tightly, something inside of him awakening. Suddenly his clothes felt scorching hot and his insides were on fire. He felt thick fluids slide down his thighs and his pheromones began to radiate in the air. He fell, but Castiel held him up, his eyes going wide. There was supposedly a small percentage of Omegas that actually went into heat after presenting, unfortunately Dean was part of that low percentage. 

 

Castiel held onto Dean, his breath picking up. He hadn't been in a situation like this before, the only time was faced with an Omega in heat was with an old friend of his, and lucky her Alpha was with her. 

 

Now he was faced with his love interests’ pheromones pouring around him, resisting the urge to pin him to the wall and knot him. 

 

“Dean I can't be here…I'm going… I'll rut if I'm too close to you...I can't.” 

 

Dean pulled him close and rubbed against him. “Cas...please I want you. I need you, Alpha,  _ now _ .” 

 

“Dean, you're in heat-”

 

Dean pulled his hair, tugging him down to kiss him and continued to rub up against him. “Take me now... please. I wanted you before my heat…”

 

Castiel couldn't resist the boy, inhaling his scent and immediately being sent into a rut. He picked Dean up and without hesitation he paced quickly to Dean's bedroom, shutting the door and stripping down. 

 

Dean panted heavily, taking off his shorts and his tank top, the articles thrown haphazardly onto the floor. Dean didn't care, he wanted Cas now. He knew he'd never wanted anything as badly as Castiel right here and now. 

 

Castiel crawled onto the bed, his lips on Dean's in an instant, one hand between the Omega’s legs and his other on the bed, grasping the sheets. He kissed down Deans neck, and the blonde-haired male wrapped his arms around the Alpha, rubbing up into his hand. The friction felt incredible, his eyes rolling back. 

 

The blue-eyed male locked eyes with green, his breath faltering momentarily before kissing him passionately, slowly circling Dean's hole and pressing against the tight ring of muscle. The Omega cried out, tremendously sensitive to the sensation of hedonism, a gasp escaping his lips. 

 

Castiel slowly slipped in another finger, caressing Dean's insides and stretching him, his cock at full attention and already rubbing against Deans. He needed to be inside him soon or he was going to go mad. 

 

“Alpha, take me now…” the alphas pheromones were driving him insane. Cas didn't hesitate, pulling his fingers out and he slipped into Dean slowly, his breath catching in his throat.

 

“Fuck...you’re so tight!” Castiel cried, his head planted in Dean's neck as he thrusted inside him, his tightness complimented by his leaking slick. Castiel felt so full inside of Dean, the young male’s eyes stuck on Castiel, his stomach twisting with pleasure and his lower region practically on fire. 

 

“H-harder!” Dean whimpered, Castiel picking up his pace to an animalistic speed. 

 

Dean cried out, hands in Castiel's hair as he was fucked into wildly. He had never experienced pleasure like this before, and he wanted to keep feeling this. He wanted Cas to pound into him more often. Sure, it stung, but the pleasure definitely outweighed the pain. He pulled his head up and kissed him, moaning into his lover's mouth.

 

Castiel flipped Dean so his chest and face were pressed against the bed, his arse high in the air. The omega gasped, his eyes rolling back as Cas thrusted back inside him, his cock hitting directly into his g-spot.

 

“Alpha! F-fuck! Th...there!” 

 

Castiel slipped his hand between Dean's thighs and began to jerk his hard member as he humped Dean, directly on top of him still.

 

“Mm… I'm going… I'm coming!” Dean cried out, his hole tightening as he spurted white ropes onto his chest and bedsheets, nearly screaming as Cas’ knot popped open inside of him, filling him up with his seed. Just as he thought he couldn't feel more pleasure, the alpha's knot rubbed against his prostate as the brunet leaned forward, biting him on the shoulder. “Mine.”

Then and there, Dean didn't think about it rather than it being a sign of possession post-orgasm. 

 

He shuddered when the swelling went down, turning over and staring into Cas’ eyes with euphoria. “Alpha…” he kissed him softly, not down from his orgasmic high yet.

 

\--

It had been a few weeks.

 

After they had sex, it was hard to think about anything else. 

 

_ “Mine.”  _

 

The words rang in his ears, and the mark on his neck throbbing. The last thing he remembered was showering with Cas, but it wasn't how he pictured. Well, it was, but it also wasn't. 

 

Cas held him possessively but he didn't talk. It's like he was holding back from saying some things. It hurt that Dean didn't know what.

 

Somehow he managed to have Castiel leave his trenchcoat--which just ended up in his nest. 

 

The nausea set in and Dean decided to see the nurse.

 

Now Dean sat in the nurse's office, a small bucket next to him, vomit on the rim of the bucket and him hunched over. 

 

“So your heat just stopped abruptly?” The nurse asked.

 

“Yeah. I mean if it didn't I wouldn't be at school. My aunt and uncle don't even know I had it. I acted like nothing happened.”

 

“I have to ask. Are you sexually active? Have you mated?”

 

Dean nodded hesitantly. “Yesterday...I guess I can call him my alpha, but I don't think he meant to… I've had a crush on him for the longest time and I went into heat, and…”

 

“He rutted and knotted you?”

 

“Y-yes.”

 

“Dean you might be-”

 

“Pregnant. Yeah. But sickness so early?”

 

“Well it was your first heat after presenting. I'm actually surprised you're not showing yet.”

 

“What do I do? Do I tell him? Oh god Bobby and Ellen are going to be pissed.” he covered his eyes. 

 

“Dean, come on they're not going to be. They'll be happy. My Omega and I mated when we were your age and it brought us closer together. But you're going to need a check up. And I'd recommend calling your Alpha.”

 

“He's a college student…this is going to ruin his life. Oh my god.”

 

“You can't talk like that, Dean. Give him a call when you're at the hospital. I'll call Ellen.”

 

Dean nodded and held his cell in his hands, staring at his lock screen. It was when he and Cas walked along the beach. He hated taking photos but Cas looked so handsome...they both looked so happy.

 

About 15 minutes later, Dean was wheeled out in a wheelchair, looking up at Ellen as her door was open. She was driving the Impala. “I don't think I have to tell you not to throw up in your car. I'll drive carefully.”

 

“I'm sorry...-”

 

“Shush. I don't want to hear your apology. Does Cas know?”

 

Dean remained silent. 

 

“I'll take that as a no. Now, do you want him in the baby's life?”

 

“I do…I'm just afraid that he won't want to be here.”

 

“If he doesn't have the balls to stay here for you and my grandbaby then he has some nerve knocking you up.”

 

“Ellen I'll call him...I hope he picks up…”

 

Dean took a deep breath and sighed, dialing Castiel’s number before putting the phone to his ear.

 

_ Brrr. Brrr. Brrr.  _

_ You've reached the voicemail of- _

 

Dean sighed. “Hey Cas...I know we haven't talked in about a week...But this is kind of important. Can you meet me at the clinic by my house? Please call me when you can.”

 

\--

Dean sat in the waiting room with Ellen who was filling out the sign-in sheet. 

 

“How long has it been since your heat ended?”

 

“About a week.”

 

_ Trust I seek, and I find in you _

_ Every day for us something new _

_ Open mind for a different view  _

_ And Nothing else matters _

 

Dean immediately picked up his phone, sighing in relief as he answered the call.

 

“Dean?” Cas’ voice was concerned. 

 

“Cas, hey.”

 

“What's wrong? Why are you at the doctors? I'm sorry I missed your call I was in a lecture but I got out early, I'm on my way-”

 

“Cas, it's okay really. I'm okay. I'm about to go to the back but I'll message you the room number. How are you going to come back though?”

 

“I'll tell them the truth. You're my mate.”

 

Dean blushed and smiled. “I'll see you soon.”

 

Dean was sat on a grey check-up bed, playing with his thumbs. 

 

“Dean, I'm here!” Cas came through the doors, wrapping his arms around him. “I'm sorry I didn't talk to you...I…”

 

“You have some nerve, boy.” Ellen pointed a finger at Castiel. “You're lucky you're his mate or I'd whoop your ass.”

 

Dean laced his fingers with Castiel’s. “I'm...pregnant…” 

\--

The drive home was very awkward between the three. Dean rode in the car with Ellen while Castiel drove behind them. 

 

“Dean I'm so sorry. I'm sorry I didn't talk to you, I thought you wanted me gone…I acted on impulse but my feelings for you are true. I want to take care of you, both of you.” he rubbed his belly.

 

Dean sniffled. “They think it's a girl…” he wiped his eyes, his heart hurting. “I thought you left me for good. I was so afraid to message you and let you know that I might be pregnant...then my body started rejecting the bite and I almost had to go on suppressants…”

 

“Dean…” he cupped his cheeks. “I felt so guilty for taking you when you were in such a vulnerable position...I thought you hated me…”

 

“I hurt for so long, Cas…”

 

“I know, Dean… I felt it too. I could barely get through my classes… I could barely eat then I missed your call...god…I'm just so grateful that...if you'd let me...can I...I want to be in your life. Permanently. I need my Omega.”

  
Dean took his hands. “I’d like that.” 


End file.
